My new words

pernicious : having a harmful effect, especially in a gradual or subtle way.
prone: likely to or liable to suffer from, do, or experience something, typically something regrettable or unwelcome.

Hindsight bias has pernicious effects on the evaluations of decision makers. Consider low-risk surgical intervention in which an unpredictable accident occurred that caused the patient’s death. The jury will be prone to believe, after the fact, that the operation was actually risky and that the doctor who ordered it should have known better. This outcome bias makes it almost impossible to evaluate a decision properly-in terms of the beliefs that were reasonable when the decision made.